The invention relates to a connection of a hollow shaft with a shaft, wherein the hollow shaft is provided with a pinion and has a slotted region facing away from the pinion, into which the shaft fits and engages in operating position. At least one clamping or tightening element, which is adjustable with respect to its diameter, encloses the slotted region and is provided for clamping the slotted region with the engaging shaft. The slotted region has at least one slot extending in an axial direction.
Such a connection is known and serves the purpose of coupling the output shaft of a motor, i.e., the motor shaft, rotation-tight with a counterpart or gear to be rotated. The slotted hollow shaft thereby allows an adaptation to various diameter tolerances of the engaging shaft to be connected. The slot width can be diminished by the tightening element which reduces the periphery, and the periphery of the slotted hollow shaft can be adapted so that this is pressed on the counterpart in friction-locking engagement. The more such slots are present, the better this arrangement succeeds, and with the usual solutions two slots lying opposite one another across a diameter or three slots evenly distributed on the periphery, respectively openly discharging on the insertion end of the hollow shaft, are therefore provided. There, one proceeds from the assumption that these free or open-ended slots result in a good pliability of the slotted region of the hollow shaft.
At the same time, however, it arises through these open-ended slots, when they are connected with the insertable counterpart, that the tightening element must be precisely adapted with its slot to one of the slots of the hollow shaft, in order to avoid relative movements between the interior of the tightening element and the exterior of the slotted hollow shaft upon tightening, and thereby avoid possible distortions, which could hinder a sufficiently tight pressing together. Furthermore, the slots are conically deformed by tightening. That is, the originally parallel-running slots are brought into an inclined position relative to one another, whereby, viewed in an axial direction, changing clamping forces and diameters can arise, which lead to motion inexactitudes of the rotating parts. There, it is even possible that the slotted element and the counterpart insertable therein can be pressed into not exactly aligning positions, so that upon rotation, owing to the alignment defect, an non-round course occurs, which additionally stresses bearings, gear teeth, etc., generates corresponding noise, and increases wear.
There thus exists the objective of creating a rotation-tight connection of the type mentioned at the outset, in which, without substantial additional expense, a precise deformation of the slotted region is made possible with uniform pressing on the counterpart to be connected. Even the coaxiality and alignment are thereby improved.
For accomplishing this objective, it is provided in connection with a slotted hollow shaft, hollow axle or sleeve that at least one slot is closed on both of its ends, and consequently also on the open end of the hollow shaft for insertion of the shaft, and that the beginning of the slot(s) facing the insertion end of the hollow shaft is spaced from this insertion end or the front face of the hollow shaft.
Instead of one or more continuous and freely opening slots, which subdivide the insertion end of the hollow shaft, hollow axle or sleeve into individual clamping tabs, an uninterrupted front face is thus created on the end of the clamping region, and in the event that all axial slots on this end are closed, an uninterrupted annular ring area is created, by which the hollow shaft or the like is stabilized on its open front face and at the same time achieves improved centering and alignment characteristics. Furthermore, there arises in the slotted region, upon pressing together and radial deformation, a more even deformation and a more uniform approximation to the respective slot boundaries, and consequently a more even diameter diminution. Still further, the inserted counterpart to be connected can be held and clamped over a larger axial area, so that even angle or alignment errors do not or hardly arise, and possible angle errors, even unintentionally brought about during insertion, are again, at least to the extent possible, compensated for by this clamping.
Moreover, the position of the slot(s) relative to the slots of the clamping or tightening element or of the tightening ring is no longer important, whereby the assembly is facilitated, primarily at difficultly viewable places. Finally, it is simpler in terms of production engineering to adhere to the processing tolerances of the hollow shaft bore, since no resilient parts must be turned or polished. The bore hole can be manufactured suitably exactly.
It is especially beneficial herein, if several slots are distributed on the periphery, and at least one of them, especially all of them, are closed on the insertion end into the hollow shaft. The clamping forces can be so much better distributed on the periphery of the shaft to be connected, the more of such slots are provided. Here, the one or another slot can indeed be open on the front end, whereby in the area of this slot, the previously sketched advantages of a closed slot would be forfeited. Nonetheless, these advantages would then result in the area of the further closed slot(s). By way of example, a slot open on the front end could lie diametrically opposite to a closed slot of the hollow shaft, so that nonetheless, even in the area of the closed slot, a more precise connection is achieved, while in the area of the open slot, the insertion of the counterpart could be facilitated, because this slot permits a short-term expansion, especially when the outside diameter of the shaft deviates only a little from the inner diameter of the hollow shaft. Likewise, in embodiments with more than two slots, one of the slots could remain open on the front end for facilitating the insertion of the counterpart with relatively small dimension differences, while the remaining slots are closed.
It is beneficial if at least two or three, preferably four or especially five slots closed on both their ends are provided distributed evenly on the periphery of the hollow shaft. This yields a good distribution of clamping forces in an axial and peripheral direction and a defined deformation of the bore in the slotted region. Since, on the insertion end, a practically circular closed annular area remains in existence, which has a similar deformation resistance as that of the hollow shaft on the opposite end outside the slotted region, practically the entire slotted region is clamped, and essentially less strong edge supports result than with open slots on the front end. Above all, the coaxiality and consequently the rotational accuracy of the connection are increased. The insertability of the counterpart can moreover be facilitated by corresponding roundings or bevels. Experiments have shown that, for a precise connection or coupling for the transmission of high torques, five closed slots distributed evenly on the periphery represent a good compromise between manufacturing expense on the one hand and connection precision on the other hand. Above all, there results here a very high rotational accuracy.
The number of slots closed on their ends can be an uneven number. An unslotted region thereby lies respectively opposite a slot on a diameter.
The slots can be constructed as elongated holes, in particular can be milled out, and their boundaries can run parallel to one another with a still open connection in an undeformed position. This permits an economical manufacture with a simple milling tool.
The axially running slot(s) closed on their ends can be arranged deflected from the coaxial or axially parallel position relative to the longitudinal central axis, even inclined at an acute angle, and in particular parallel to one another. With equal axial extension of the slots, the absolute slot length can thereby be enlarged, which can lead to a simpler radial deformation of the slotted region.
By axial direction of travel of the slot, not only a coaxial, axially parallel, or an arrangement following the jacket lines is to be understood, but also one in which the slot(s) run(s) in an axial direction and at the same time somewhat inclined to the longitudinal central axis or to the jacket lines.
The spacing of the slot(s) from the insertion end or the front face of the hollow shaft can approximately correspond to the radial wall thickness or the thickness of the hollow shaft, or be larger or smaller. A sufficiently tight circular ring area adjacent to the front face is created, which upon clamping the slotted region has the desired resistance moment.